In industry nowadays, success or failure depends in part upon knowing the up-to-date status of various assets. For example, in the freight delivery business, up-to-date knowledge of the location and, in some instances, the environment of various assets, such as pallet goods, is critical to efficient and reliable operations. Failure to maintain up-to-date status information can result in temporarily lost assets, sub-optimal use of the assets, and in the case of freight delivery, missed or late deliveries.
Recently, technologies have been developed that greatly assist in tracking locations of assets. For example, global positioning systems (GPS) use wireless signals transmitted by earth-orbiting satellites to calculate the position of a receiving device. Although relatively expensive, GPS receivers are capable of providing relatively accurate location information for virtually any point in the world.
More recently, radio frequency identification (RF or RFID) systems have been developed in which tracking or transmitting devices, often referred to as “tags,” wirelessly communicate with readers. RF tracking systems are typically used in parcel tracking and sorting, container tracking, luggage tracking, retail tracking, warehouse tracking and inventory operations. The tracking devices may be either passive or active. Passive devices absorb signals transmitted by the reader and retransmit their own signals, such as identification information. While a passive device does not require a local power source, its resulting transmit range is relatively short, typically less than 1-2 meters. In contrast, an active device, which sends a signal to indicate its location, includes a local energy source (such as a battery) that improves transmission range. Depending on the wireless signal system used by the device, the range may be on the order of several meters or several hundred meters, or even miles. Regardless of the types of device used, knowledge of the location of the device allows users to identify the location of an asset that has the tracking device attached thereto.